Project Description /OverviewNabih Youssef Structural Engineers (NYA) provided structural engineering services for the Tenant Improvement of Gensler's new office located at City National Plaza in Los Angeles. The project consisted of three components: a new mezzanine structure, a 3rd floor opening (in a previous attic area) and a new roof skylight.
The existing space was converted from two floors to three by adding a steel constructed mezzanine level (11,200 sf) that is hung from the top floor, to allow for an open first floor plan. The gravity system consisted of lightweight concrete filled metal deck, spanning to Wide Flange beams. The beams are supported by High Speed Steel hangers off the long-span story trusses above the 1st floor with direct connections to the existing building columns. The mezzanine is laterally restrained by the existing building moment frames, by tying into them at each corner.
The new skylight opening at roof level (approximately 50 sf), is supported by upturned steel wide flange beams around the perimeter of the opening, and sit on top of the existing roof beam supports. The opening on the 3rd floor is approximately the same size as the skylight above, with the exception of two cantilevered pieces. The slab is supported by keeping the existing floor beams in place and welding up the connections to create new cantilevered beams.